If you want a portable rig that is going to be on par with your own home rig, you are looking at a bigger investment than $250 for an iPod, IMO, at least if you are coming at it with perfectionist expectations. The big drawback in portable devices is the crappy opamp output. Best to go with a LOD (line out dock) into a portable amp into some fine buds. At the top of that range here's an example of what a great rig would cost:
Classic iPod or iTouch if you want all the added BS $299
ALO Audio LOD $200
RSA SR71B Balanced* Portable Amp $650 OR Triad Audio Lisa III $600
JH16 earbuds $1200
*Whiplash TWAG Recable JH Audio to Balanced $225
Total = @ $ $2300 (welcome to the world of hi-end portable)
On a budget, I've found that my iPhone via UE10Pros is a fine compromise.
Classic iPod or iTouch if you want all the added BS $299
ALO Audio LOD $200
RSA SR71B Balanced* Portable Amp $650 OR Triad Audio Lisa III $600
JH16 earbuds $1200
*Whiplash TWAG Recable JH Audio to Balanced $225
Total = @ $ $2300 (welcome to the world of hi-end portable)
On a budget, I've found that my iPhone via UE10Pros is a fine compromise.